ping_lookup() does not acquire the table spinlock, so iteration should
use hlist_nulls_for_each_entry_rcu().

Spotted during code review.

Fixes: dbca1596

 ("ping: convert to RCU lookups, get rid of rwlock")
Cc: Eric Dumazet <[email protected]>
Signed-off-by: Florian Westphal <[email protected]>
Link: https://lore.kernel.org/r/[email protected]


Signed-off-by: Paolo Abeni <[email protected]>